China.org.cn reports that authorities know what this silver torpedo-like device was used for and disguised to look like:

It is now confirmed that the unmanned underwater machine, disguised to look like a torpedo, is an intelligence device capable of taking pictures with fiber-optic and satellite communication. It was secretly placed in the water by a foreign country to obtain information on the Chinese navy fleet’s operations at sea.

Experts worried that the acquired information may have been sent back and that there are many other similar devices that haven’t been detected in the water, which pose great hidden dangers to information security in the South China Sea.

Hainan Province, which sits at the gateway to the disputed South China Sea, is home to the Chinese Navy’s most strategic naval complex. On the southern end of the island, there are a series of massive naval installations, many of which are centered around the Chinese Navy’s burgeoning ballistic missile nuclear submarine fleet. These include shipyards, large dock areas where entire flotillas can assemble and be resupplied and what is reported to be a massive under-mountain submarine base network that is accessed via a camouflaged tunnels.

If this device is indeed a unmanned underwater spy vehicle of sorts, it obviously would have a huge amount of things to look at and listen to in and around Hainan Island. But why would the Chinese authorities publicly admit that it was a foreign spying device at all? Maybe to make sure that people know what something like this is if they spot one in the future so that it can be captured or destroyed, and possibly to let external powers know they have discovered their mode of spying.

The strange event is also a reminder of the unmanned future of undersea warfare. A device like this, or even one larger than it (if it truly was only about three feet or so long) could have been deployed miles from the Hainan Island Naval Complex, and if it was built in a “sheep dipped” manner, where there are no technologies or insignia that give away the device’s origin, it could be sent even on a one-way reconnaissance missions with little potential for repercussions.

As far as how such a device like this could work, it could be deployed by a submarine miles off the coast, or brought closer by special operations divers. Once released, it could lay in wait near large submarine naval bases, preserving its battery power until something of interest was detected acoustically. It could then rise off the sea floor and obtain key acoustic signatures of vessels coming and going from the area.

It could also be used as a probe that enters into port areas to visually spy on enemy naval operations. Once it has collected its data, it could pop-up to transmit its findings via satellite or swim to a fiberoptic entry point or battery and information bank on the seafloor and transfer its data there, and even possibly recharge its batteries. After its mission is over, it could self destruct, sink to the sea floor, or be recovered by special operations forces or by a larger submarine miles from its target.